November 12, 2003:
Imagine you’re in California. It’s July, the middle of summer.
sun rises early; bright rays warm the ground. It’s a great day to be
outside. Then, suddenly, it begins to snow - not just a little
flurry, but a swirling blizzard that
Using data archived by
NOAA’s Space Environment Center, Francis Reddy created this plot of
sunspot number and X-class solar flares during the last three solar
doesn’t stop for two weeks.
That’s what forecasters call unseasonal weather.
It sounds incredible, but "something like that just happened on the
sun," says David Hathaway, a solar physicist at NASA’s Marshall
Space Flight Center.
Only a few weeks ago
solar activity was low. The face of the sun was nearly blank - "very
few sunspots," says Hathaway - and space weather near Earth was
"Mild is just what we expect at this point in the 11-year solar
cycle," he explains.
"The most recent maximum was in 2001, and solar activity has been
declining ever since."
Then, suddenly, in late October
the sun began to behave strangely. Three giant sunspots appeared, each one
larger than the planet Jupiter.
In California where smoke from wildfires dimmed the sun enough to look
straight at it, casual sky watchers were startled by the huge blotches on
the sun. One of them, named "sunspot 486," was the biggest in 13 years.
The October 2003 CME was
Sunspots cause solar flares and, usually, the biggest flares come from the
The three giant sunspots unleashed eleven X-class flares in
only fourteen days - equaling the total number observed during the previous
twelve months. "This was a big surprise," says Hathaway.
The effects on Earth were many: Radio blackouts disrupted communications.
Solar protons penetrated Earth’s upper atmosphere, exposing astronauts and
some air travelers to radiation doses equal to a medical chest X-ray.
Auroras appeared all over the world - in Florida, Texas, Australia and many
other places where they are seldom seen.
Researchers rank solar flares according to their x-ray power output.
C-flares are the weakest. M-flares are middling-strong. X-flares are the
Each category has subdivisions: e.g., X1, X2, X3 and so on. A typical
X-flare registers X1 or X2. On Nov. 4th, sunspot 486 unleashed an X28 flare-
the most powerful ever recorded.
"In 1989 a flare about half that strong caused a widespread power blackout
in Quebec," recalls Hathaway. Last week’s blast was aimed away from Earth,
so its effects on our planet were slight - a bit of good luck.
All this happened two years after solar maximum, which raises a question: is
something wrong with the solar cycle? Is the sun going haywire?
"Nothing’s wrong," reassures
Hathaway. The sun isn’t about to explode, nor
is the sunspot cycle broken.
"These latest sunspots were whoppers," he allows, "but sunspot counts
averaged over many weeks are still declining as predicted. We’re still on
course for a solar minimum in 2006."
Indeed, it’s possible that what we’ve just experienced is a normal part of
the solar cycle, speculates Hathaway.
"There’s a curious tendency for the biggest flares to occur after solar
maximum - on the downslope toward solar minimum. This has happened during
two of the last three solar cycles."